When Sylvia and Korob are seen in their true form at the end of the episode you can quite clearly see the strings. Thankfully the remastered episode fixes this.

Worst Moment :

The giant cat chasing them around. Sorry, but this just looks terribly, terribly unconvincing and quite funny.

Body Count :

Crewman Jackson and the two aliens, Sylvia and Korob.

Factoid :

This was the Halloween episode, hence the witches.

This is Walter Koenig's first episode as Pavel Chekov, although Chekov himself likely served aboard the ship during the first season, as Khan recognised him by sight in the movie "Star Trek II: The Wrath of Khan"

Writer Robert Bloch based this episode loosely the short story "Broomstick Ride", which he also wrote.

Theo Marcuse, who played Korob, was killed in a car accident a month after this episode aired.

Plotline

The Enterprise is investigating the planet Pyris VII, but the landing party - comprising Sulu, Scott and Crewman Jackson - is overdue for their routine check in. Jackson finally contacts the ship asking to be beamed aboard, but when he appears he collapses to the floor, dead. Amazingly, a voice from his mouth informs Kirk that the ship is cursed!

Kirk beams down with Spock and McCoy, leaving Assistant Chief Engineer DeSalle in command of the ship. They arrive in a fogbound environment, quite at odds with what their sensor readings indicated. Detecting lifeforms nearby the landing party investigates, only to be confronted with a ghostly apparition - three witches, warning them to leave or face disaster. Undaunted, the officers press on and discover a large castle. They enter and begin to explore, but a section of floor collapses beneath them, knocking them out.

They wake to find themselves chained in a dungeon. Scotty and Sulu appear, but they appear to by drugged or hypnotised, not recognising their fellow officers. They free the landing party and take them at gunpoint from the room to meet a robed man. He is, apparently, some kind of magician - complete with a wand and black cat. The man's name is Korob, and he appears intent on getting the Enterprise officers to leave as soon as possible. Korob claims that the events have been staged to test the Enterprise crew, but he clearly seems to be hiding the truth.

A woman, Sylvia, enters. She demonstrates her own power to Kirk, holding a small model of the Enterprise over a candle - and action which causes the real ship in orbit to grow unbearably hot! Although she spares the ship, Korob seals the model in a glass block, which paralyses the real ship within a strange forcefield.

Kirk and Spock are taken to the dungeon, whilst Sylvia questions McCoy. She argues with Korob about their plans - Sylvia states that she enjoys the sensations she is experiencing in her present form, as apparently their normal existence does not afford them such. Korob argues that they have a mission to complete, but Sylvia seems in favour of abandoning it.

Sylvia brings Kirk back to talk, and reveals that she has become enamoured of him. She is thinking of getting rid of Korob and keeping Kirk for herself. Kirk plays along for information, and learns that the "magic wand" is a transmuter, able to reform matter into different forms - this is how the pair create the various strange things Kirk has encountered. She realises the deception and has Kirk returned to the dungeon.

Korob, beginning to fear Sylvia's intentions, releases the Enterprise and Kirk and Spock. He expresses regret for how things have gone, wishing there could have been peaceful contact. As they attempt to flee, Kirk and Spock encounter Sylvia's black cat, only grown to enormous size. The cat kills Korob, and Kirk grabs his transmuter wand and escapes. Sylvia demands the transmuter wand, which is more powerful than her own device, but as Kirk begins to hand it over he instead smashes it. At once the castle and everything within it vanishes, leaving only Sylvia and Korob in their true form - two small, vaguely birdlike aliens who quickly die. With the menace defeated, the officers beam back to the ship.

Analysis

This is rather transparently a "halloween" episode, with the plot basically serving as an excuse to throw all sorts of scary images onto the screen - witches, voices from the dead, dark castles, etc. It's all pretty thin stuff, and to be honest it never really works. The most painful moment is the "giant cat". Sorry, but despite the best efforts of the characters and the special effects, this is comical rather than scary. The obvious puppets of Sylvia and Korob are also quite comical, but thankfully this at least was repaired in the remastered version.

Overall, just not a good episode.

Special Edition

The remastered version has the usual improved exterior shots of the Enterprise and a much nicer planet. Notably, the extremely obvious strings used to control the alien puppets of Sylvia and Korob have been erased. Also, we get a wide shot showing the whole of Sylvia and Korob's castle.